A Devicenet Explicit Messages - Omron DRT2 SERIES DEVICENET SLAVES - OPERATION MANUAL 04-2008 Operation Manual

DeviceNet explicit messages sent from the Master Unit to a DRT2-series Smart Slave can be used to read or
write any parameter of a specified Smart Slave.
The Smart Slaves process the commands sent from the Master and then return responses.
Basic Format of Explicit Messages
The basic format of each command and response is shown below.
Command Block
Destination Service
node address
code
Destination Node Address
The node address of the Unit that is sending the explicit messages (commands) is specified as a single-byte
hexadecimal.
Service Code, Class ID, Instance ID, Attribute ID
The parameters used for specifying the command, processing object, and processing content.
Note The number of bytes designated for Class ID, Instance ID, and Attribute ID depend on the Master Unit.
When sent from an OMRON DeviceNet Master, the Class ID and Instance ID are 2 bytes (4 digits), and
Attribute ID is 1 byte (2 digits).
Data
Data is not required when the read command is used.
Response Block
Normal Response Block
Number of bytes Source node
received address
Error Response Block
Number of bytes Source node
received: address
0004 Hex (fixed)
Number of Bytes Received
The number of bytes received from the source node address is returned in hexadecimal. When an error
response is returned for an explicit message, the number of bytes is always 0004 Hex.
Source Node Address
The node address of the node from which the command was sent is returned in hexadecimal.
Appendix A
DeviceNet Explicit Messages
Class Instance
ID ID
Service code
Service code
Attribute Data
ID
Data
Error code
469